Waste polyethylene terephthalate (PET) polymer is neither environmentally biodegradable nor compostable, and thus suffers from disposal problems. Recycling has become a viable alternative to the long-term accumulation of garbage, and there is substantial availability of recyclable PET waste. For example, post-consumer PET derived from soft drink bottles is available in bulk for relatively low cost. Bottle-grade PET is known to be of high quality among the various PET grades, and is available particularly as washed flakes. There are major incentives from environmental perspectives and governmental regulatory directives to find new and improved uses for PET waste.
As an unreinforced, semi-crystalline thermo-plastic polyester, PET has excellent wear resistance, excellent hardness and stiffness, very good creep resistance, low coefficient of friction, high flexural modulus, and superior dimensional stability. Nevertheless, PET—particularly following melting and resolidifying of post-consumer recyclable waste—can be quite brittle and as such can be inappropriate in some applications.
U.S. Pat. No. 6,583,217 B1 to Li et al. is directed to a composite material composed of fly ash and waste PET. Melted waste, chemically unmodified PET material and fly ash particles are mixed in a vessel to disperse fly ash particles in the melted PET material. The resulting mixture then is cooled to solidify the melted PET material to form a composite material having a matrix comprising PET and dispersoids distributed in the matrix and comprising fly ash particles.
Despite known composite materials, there exists a need for alternative PET materials with less susceptibility to brittle behavior. More particularly, there exists a need for a PET material appropriate for use in coating metals used in mechanically rigorous applications. Also, there exists a need for a composite material formed of cement and recycled PET, along with a method of making same.